Recharge flooding of collieries in South Africa
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Date
2020-08
Authors
Lukas, Eelco
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State
Abstract
Coal mining has been documented in South Africa as far back as 1838 and undoubtedly contributed
significantly toward the economy as well as job creation (Barnes and Vermeulen 2012).
Many mines in South Africa have changed the geology on a localized level by taking out the coal seams.
The change in geology also changed the geohydrology. The voids that are left to fill with water. Most
of that water will be groundwater, but some will be surface water and stormwater. In the
geohydrology, we talk about the recharge of a mine. The recharge is depending on several factors,
some depending on the physical mining methods and others depending on the geological setting.
Recharge and mine flooding (opencast or underground) is nothing new; it occurs in every mine from
the first day the mine was created. Recharge is a natural process; inundation is the act of intentionally
flooding of land that would otherwise remain dry. Where inundation floods a mine using a single or
multiple pumping locations, the recharge is a phenomenon that occurs over the full extent of the
mine.
Although recharge is often considered to occur equally over the full extent of the mine, this is not true.
Many factors influence the recharge, such as rainfall and rainfall intensity, surface topography, depth
of mining, geological structures, presence of subsidence, surface structures, and in case of an opencast
mine, the state of rehabilitation.
There are different ways to express recharge and is commonly defined as a volume [L³], typically m³.
Recharge rates are expressed either as a flux [L³T-1
] or as a flux density [LT-1
] (Nimmo, J.R., 2005).
Because recharge is depending on rainfall (without rainfall no recharge), the recharge is usually
expressed as a percentage of the rainfall.
Description
Keywords
Thesis (Ph.D. (Geohydrology))--University of the Free State, 2020, Coal mining history -- South Africa -- 1838, Coal mining -- Economy -- South Africa, Coal mining -- Geohydrology